The present invention relates to an apparatus for delivering a conductive liquid to an apparatus having an electrical voltage charge. More particularly, the invention relates to an apparatus for spraying conductive paint under electrostatic voltage spraying conditions.
It is well known that the utilization of electrostatic voltage assists in the spraying of articles and greatly improves the efficiency of the overall spraying system. When paint is sprayed in the presence of an electrostatic field, the paint spray particles pick up electrostatic voltage charges and are, therefore, attracted readily to a grounded article.
This electrostatic charging process greatly increases the number of paint spray particles which become applied to the article thereby greatly reducing the amount of paint overspray which would otherwise pass beyond the article.
A particular problem results from attempting to spray water-base coating materials in an electrostatically-charged spraying system. The problem arises because the water-base component is conductive to a greater or lesser degree; and therefore, the electrostatic voltages can be directed into the liquid column at the point of discharge into spray particles and the liquid column itself can form a conductive path back to the point of origin of the liquid. In this situation, all of the components in the liquid coating delivery system can become voltage charged and can present a hazard in the work environment. One solution to the problem is to voltage isolate the entire spraying system, preventing any user from coming into contact with the system components. Another solution is to voltage isolate certain components of the liquid delivery system, particularly those components to which a user might become exposed. A further solution is to voltage isolate the liquid delivery column to limit the extent to which the liquid column can become voltage charged, to thereby prevent all components upstream from the voltage isolation point from becoming voltage charged. The present invention relates to this latter approach to improving the safety and utilization of electrostatic spraying systems in connection with conductive liquid coating materials.
It is a principal object of the present invention to provide a voltage isolation device in the liquid flow path of an electrostatic coating system to isolate electrostatic voltage charge accumulation.
It is another object of the present invention to provide a voltage block or voltage isolation device for connecting a grounded liquid supply system to a voltage-charged liquid spraying system.